A difficulty arises in the travel industry, particularly in connection with air travel, in that passengers often have no more than a vague idea as to the actual weight of a travel bag when they go to check in at e.g. an airport. If they try to weigh their bags at home, this is often difficult and awkward. Added to this, there is often a maximum weight which is permitted, or is permitted without an “excess weight baggage” charge. This is usually the same for most carriers for journeys of a particular class, e.g. all flights abroad. Weighing bags at a check-in and dealing with excess weight baggage substantially increases the workload of staff, and eventually the cost of flights.